This invention relates to suspension struts and, more particularly, to frictionally damped suspension struts. While one presently preferred embodiment of the invention is disclosed herein for application to suspension struts such as those used to support the cab on certain types of heavy trucks, the invention is not limited to such applications and may be used with other types of suspensions and vehicles, including without limitation as the front and/or rear suspensions of lightweight passenger vehicles, and in other applications.
Frictionally damped suspension struts, such as that disclosed in U.S. Pat. No. 4,475,722 and 4,473,216, are suitable for providing differential jounce and rebound damping forces. That is, the frictional damping force obtained during compression of the strut under jounce conditions may be different in magnitude than the frictional damping force obtained during extension of the strut under rebound conditions. Indeed, these struts typically provide a frictional damping force which is greater during rebound conditions than jounce conditions. In the struts disclosed in the aforesaid United States Patents, this is accomplished by the provision of different wedge angles on the damper wedges and their associated upper and lower wedge rings. In some practical applications, however, the differential between the frictional damping forces obtained during jounce and rebound conditions is insufficient to provide satisfactory ride characteristics.